In the comments for this item: https://www.sparkfun.com/products/10217, MikeGrusin (from SparkFun) replied (https://www.sparkfun.com/products/10217#comment-511a8f68ce395ff505000000) about how to modify the basic lipo charger to handle smaller batteries. Essentially, you take the 2k PROG resistor out, and replace it with a larger resistor. Per the datasheet, you should replace it with a 40k resistor to bring the charge down to 40mAh, which is appropriate for the smaller batteries.

I used a 33k surface mount resistor that I had lying around. It was one size up from the old resistor, but it was fine. Alternately, you can use a through-hole resistor if you solder carefully. So far, my tiny 40mAh battery is charging fine, and is not at all warm. Obviously, YMMV.

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